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VOLUME 56, ISSUE 1/2015

Growth ring studies of the anatomical and chemical cell parameters and the density distribution in the wood of Sweet chestnut (Castanea sativa Mill.); Part 2: Comparative analysis of the measurement results

Language: German
Pages: 5 - 10
Authors: Felix Losemann, Gerald Koch, František Hapla

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The research goal of this study was a comparative investigation of ring-shake on the cell level in wood samples with and without a crack. The anatomical and chemical investigation were conducted in six exclusive sample selections, representing six Castanea sativa Mill. trees from three differently managed plots. Depending on the used measurement techniques the number of single measurements varied between 10² and 104 values. A statistical analysis of microscopical data was conducted to investigate the differences between samples with and without crack. No clear tendencies could be revealed. The analysis of box plots for the samples with cracks showed a higher mean variability of earlywood- and latewood-vessel diameters. An

increase of the cell wall thickness of the libriform-fibres within the latewood was found too. The higher variability of wood density in cracked samples was also observed by a computed tomography. The results lead to the hypothesis that the variability of the mean values of the earlywood- and the latewood-vessel diameters as well as the thickness of the libriform-fibres in the latewood could be explained

by the variability of the wood density within the radially gradient. An UMSP-investigation revealed significantly higher lignin content in two of three cracked samples. This could be a possible cause for high brittleness and anisotropy of the xylem.

Moisture performance testing of wood; Practical experience in the field

Language: English
Pages: 11 - 19
Authors: Linda Meyer, Christian Brischke, Martin Kasselmann

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Different methods are used to characterize the moisture performance of wood. These methods can be divided into direct and indirect methods. Furthermore they can be distinguished by characteristics like continuous or periodical measurements and measuring local or global moisture content (MC). Each measuring method has certain peculiarities that need consideration when designing a test set-up and conducting MC measurements in the field. Therefore reports are given on practical experience with measuring and monitoring wood MC to determine the moisture performance of wood under lab and field conditions. Results from different studies that have been conducted during the last four years are presented. The aim was to enhance the understanding of factors influencing gravimetric and resistance based MC measurements. The results of the different studies pointed on the potential of moisture monitoring to serve for an improved interpretation of field test data. However, they also highlighted the need for considering several significant factors such as measuring depth and position, the effect of weathering and the identification of the most critical conditions within a given set up.

Investigations on box-type windows for the combined realization of future thermal insulation requirements and improved sound insulation properties

Language: German
Pages: 20 - 28
Authors: Kerstin Schweitzer, Jens Wiedemann

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The search for high-performance windows in terms of heat protection and sound insulation inevitably leads to double-shell design principles. That box-type windows are particularly suited to realize such performance characteristics, is known. However, so far a separate optimization of both properties dominated due to partly contrarian design rules. Investigations on modern box-type windows for use in new and existing buildings had the aim to combine both properties in one construction element. While a prior article (Wiedemann und Schweitzer, 2014) discussed the flow conditions of the entrapped air in detail, the following one focuses on the combination of heat and sound insulation properties.

Cross industry innovation process for finding new mechanical disintegration technologies of wood

Language: German
Pages: 29 - 34
Authors: Ulrich Müller, Oliver Vay, Alejandro Martinez-Conde Lopez, Stephan Frybort, Thomas Krenke, Johannes Konnerth, Alfred Teischinger

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The primary material wood is used in huge quantities and is typically fragmented by tradition based technologies like sawing, peeling, hammer milling, refining and others in a first process step. A compulsory need of radical innovation was identified in order to amend current fragmentation technologies. Existing ones are not able to consider the mechanical potential of the material. A couple of these technologies exhibit insufficient yield of high quality material. We hypothesize that it is possible to fractionize wood in a different and also more efficient way than the existing ones most notably by using non-cutting based technologies retaining the natural optimized structure of wood. Wood composites produced out of these optimized particles are assumed to have improved mechanical properties. Based on an interdisciplinary and cross innovation process new technologies for mechanical disintegration of wood were investigated in different projects. The article presents some examples of new mechanical disintegration methods and shows the basic principle of a cross industry

innovation process (CIIP).

Review: State of the art of cutting force examinations of wood; Part 2

Language: German
Pages: 35 - 44
Authors: Thomas Krenke, Stephan Frybort, Alejandro Martinez-Conde Lopez, Ulrich Müller

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Since the middle of the 20th century several studies concentrate on the mathematical description of the cutting process of wood. In order to resolve this problem, empirical as well as analytical approaches were applied. Despite extensive research until now still no practical as well as a complete description of the interaction process of wood cutting exists. For this reason the aim of the following work is bringing together different approaches to develop an accurate and yet user-friendly explanation of cutting forces in wood, likewise in the metal working industry. The first part dealt with the geometric

principals of the cutting process. Furthermore previously developed models, especially empirical models, were presented. In this part of the work the state of the art of analytical approaches for the description of cutting models are presented and their applicability on wood is discussed.

Review: Current testing methods for modern lightweight materials for furniture and interior design

Language: German
Pages: 45 - 50
Authors: Max Britzke, Jan Herold, Stefan Lippitsch

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For the use of conventional wood-based materials such as chip-board and fibre-board in furniture industry there are a number of different test methods. They allow a characterization of the materials according to their intended use. In contrast, the material behaviour of lightweight furniture materials, such as sandwich panels with paper honeycomb core, is so far only insufficiently described by test methods. Due to the complex structure (sandwich construction) of such materials there is the need of the development of appropriate test methods.

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